Understand Cancer & Reduce Cancer Risk | Dr. Peter Attia & Dr. Andrew Huberman
00:00:00.000 | what about cancer? Again, nobody wants cancer. Uh, we've all known people who've died of
00:00:07.360 | cancer, um, or have had cancer. What can be done to reduce one's risk of cancer?
00:00:14.560 | Well, you asked earlier about the numbers. So let's throw some numbers out there, right?
00:00:18.480 | So globally we're talking about 11, 12 million deaths per year, about half the number of
00:00:23.360 | ASCVD, still a staggering number. Um, at the individual level, put it this way, somewhere
00:00:31.120 | between one in three and one in four chance, anyone listening to this or watching this
00:00:35.460 | is going to get cancer in their lifetime.
00:00:37.600 | But what's the probability they will die from that cancer?
00:00:41.140 | Half of that, about a one in six chance of dying.
00:00:43.640 | Okay. So is it true that every male gets prostate cancer? Most, in other words, on their deathbed,
00:00:50.240 | many men will die with prostate cancer and some will die from it. You and I have prostate
00:00:56.720 | cancer right now.
00:00:58.340 | Thank you for informing.
00:00:59.480 | Yes. Hopefully we will not die of it. We should not die of it. Prostate cancer, colon cancer
00:01:04.720 | are cancers that no one should ever die from because they're so easy to screen for. They
00:01:09.640 | are so easy to treat when they are in their infancy, um, that it's totally unacceptable
00:01:14.640 | that people are dying from this. There are other cancers for which I can't really say
00:01:17.560 | that. Breast cancer, much more complicated. Pancreatic cancer, much more complicated.
00:01:22.440 | Glioblastomae multiforme, much more complicated. So there, you know, as you said a second ago,
00:01:27.120 | cancer is not a disease. It is a category of diseases. Each, it's not just that each
00:01:32.360 | organ is different and breast differs from pancreatic. It's that within breast cancer,
00:01:37.480 | ER, PR positive, HER2/neu positive is a totally different disease from the triple negative
00:01:42.320 | breast cancers.
00:01:43.360 | Those with BRCA mutations or non-BRCA mutations.
00:01:46.000 | Oh, yeah.
00:01:47.000 | Even putting that aside, just looking at the hormone profile of the individual breast cancers,
00:01:51.240 | they're totally different diseases. So it's not just that breast cancer is different from
00:01:55.360 | prostate cancer. It's that all breast cancers are quite different.
00:01:59.480 | Maybe I should frame the question a little differently than given the vast number of
00:02:03.080 | different types of cancers and categories within those.
00:02:05.720 | Your question is still a fair one. I just wanted to throw that caveat out there. So
00:02:08.240 | now to your question. Okay. So what do we know? It turns out that we can very comfortably
00:02:15.040 | speak to several things. One is the role that genes play. So maybe I'll just spend one second
00:02:26.120 | on a gene 101 thing for the viewer. We want to differentiate between what are called germline
00:02:33.280 | mutations and somatic mutations. So your germline and my germline are set. When we were born,
00:02:42.800 | our germline mutations... Any mutations we have in germline genes are inherited from
00:02:47.880 | our parents.
00:02:48.880 | They're non-negotiable.
00:02:49.880 | They're non-negotiable. You got those things. So question one is how much of cancer results
00:02:58.060 | from those types of genetic mutations? And the answer is very little, less than 5%. So
00:03:04.080 | very... You mentioned one a moment ago, BRCA. Okay. So mutations in BRCA are germline mutations.
00:03:10.520 | A woman will get a BRCA mutation from one of her parents. And we will often have a sense
00:03:17.540 | of that just from the family history. When mom and sister and aunt and grandmother had
00:03:23.120 | breast cancer, you've got a breast cancer gene. Now it might be BRCA. It might be another
00:03:28.120 | gene that's not BRCA, but there's no ambiguity. And we test for these genes mostly just for
00:03:34.760 | insurance purposes, frankly, but there's no ambiguity that that was a germline transmission
00:03:40.100 | of a gene that is driving cancer. But 95+% of cancers are not arising from germline mutations.
00:03:49.920 | They are arising from somatic mutations or acquired mutations. So the question then becomes
00:03:56.860 | what is driving somatic mutation? And the two clearest indications of drivers of somatic
00:04:06.480 | mutation are smoking and obesity. Smoking we've talked about. Let's put that aside for
00:04:12.680 | a moment. I'm so surprised about obesity. I don't know why I'm surprised, but I've never
00:04:17.640 | heard this. I'm probably just naive to the literature. Yeah. So obesity is now the second
00:04:23.400 | most prevalent environmental driver of cancer. Now I will argue, and I think I argue this
00:04:30.240 | in the book, hopefully pretty convincingly, I don't think it's obesity per se. I think
00:04:35.320 | obesity is just a masquerading proxy. What is obesity? Obesity simply is defined by body
00:04:42.040 | mass index. Well, first of all, I don't think I'm obese, but I'm way overweight on BMI.
00:04:49.040 | You probably are too. So, you know, let's just ignore that. I'm clinically diagnosable
00:04:52.920 | as obese. Are you? Oh, no. Well, not clinically. That would be BMI over 30. I don't think you're
00:04:58.300 | probably there. No, but if I measure my weight by height... Yeah, yeah, yeah. My BMI is probably
00:05:04.320 | 27 or 28. Okay. It's been a little while since I've checked. I only know body fat percentages
00:05:09.400 | and things like that. So basically, like BMI is a far from perfect proxy, but at the population
00:05:15.040 | level, it's what we use. I wish we would get off it, by the way. I think it's really crap.
00:05:20.900 | Because it doesn't take into account lean versus non-lean tissue. Yeah. I think we could
00:05:25.480 | get better data if we looked at waist to height ratio. That's a way better metric. So this
00:05:32.360 | is just a quick test for everybody. I'm going to argue your BMI is less relevant to me than
00:05:39.240 | your eye color. But if your waist circumference is more than 50% of your height, you should
00:05:45.960 | be concerned. Okay. Well, then I'm okay. Yeah, you're fine by that metric, right? But that's
00:05:50.960 | important. So if you're six feet tall, your waist better be under 36 inches. And if it's
00:05:57.180 | over, I would argue that's the definition of obesity, not your BMI being over 30. So
00:06:05.080 | back to this issue, because we're using such a crude measurement, it basically is catching
00:06:10.720 | a whole bunch of stuff. But the question is, what's driving it? And I think if you really
00:06:15.680 | look at the physiology of cancer, I don't think it's obesity. I think it's two things
00:06:23.980 | that come with obesity, insulin resistance, which is two-thirds to three-quarters of obese
00:06:31.380 | individuals are insulin resistant, and inflammation. And I think those two things, with the inflammation
00:06:37.800 | and the immune dysfunction, with the insulin resistance and the hyper basically tonic growth
00:06:44.960 | stimulus that's coming, that's what's driving cancer. So again, is it because a person is
00:06:50.120 | storing extra fat and their love handles that that's driving the risk of cancer? No. Those
00:06:56.800 | are just two things that are coming along for the ride. So beyond those two things,
00:07:03.800 | and along with certain... There are also certain environmental toxins we absolutely know are
00:07:07.640 | doing this, right? So we understand that people who have exposure to asbestos have a much
00:07:12.100 | higher risk of certain types of lung cancers and things like that. But for the most part,
00:07:16.360 | those are our big risks. Beyond that, we talk about alcohol in certain cases, absolutely.
00:07:22.480 | Alcohol is a carcinogen. The dose part still isn't clear to me. I don't know, is one drink
00:07:30.360 | a day moving the needle much on cancer risk per se? It's not clear.
00:07:35.400 | And it might depend on those genetic predispositions.
00:07:38.960 | So, yeah, if step one is don't get cancer, you have no control over your genes, you have
00:07:48.280 | control over smoking, you have control over insulin sensitivity. I wish I could sit here
00:07:55.560 | and tell you that there is a proven anti-cancer diet, or that if you do X amount of exercise
00:08:03.860 | per week, you're going to not get cancer. We just don't have a fraction of the control
00:08:11.080 | over cancer that we have with cardiovascular disease. We don't understand the disease well
00:08:16.120 | enough. So we don't understand kind of the initiation process and the propagation process.
00:08:23.760 | And we have to rely much more on screening.
00:08:28.540 | Are there good whole body screens for cancer? In other words, can I walk into a tube and
00:08:37.920 | or a cylinder rather, and get screened for the presence of tumors any and everywhere
00:08:44.240 | in the body outside the brain? Because the brain is a little harder to get to, right?
00:08:47.440 | Believe it or not, the brain is actually pretty easy to screen for.
00:08:50.240 | Because it's so fatty and floating in water.
00:08:53.120 | Well, and also the head, when you put the head into an MRI scanner, there's no movement.
00:08:58.240 | It's the least motion artifact is in the brain. So when you use something called diffusion
00:09:02.500 | weighted imaging with background subtraction in an MRI, a technology that was actually
00:09:06.460 | pioneered in the brain for stroke identification, it's also really good at looking for tumors
00:09:12.620 | as well.
00:09:15.260 | So let me make the argument for why screening matters. Because this is, again, kind of an
00:09:21.220 | area where I go far down a rabbit hole in a way that I think traditional medicine would
00:09:27.060 | argue against.
00:09:29.540 | So my argument for screening is an argument at the individual level. And it goes as follows.
00:09:37.800 | To my knowledge, there is not a single example of a cancer that is more effectively treated
00:09:44.980 | when the burden of cancer cells in the body is higher than when it is lower.
00:09:51.740 | So the two examples I think I talk about in the book are colon cancer and breast cancer.
00:09:56.260 | So when you take an individual with stage four colon cancer, that means that the cancer
00:10:01.560 | has left the colon and is now outside of the colon. So it's usually in the liver at a minimum,
00:10:07.180 | potentially in the lungs or in the brain.
00:10:10.860 | That person's five-year survival is very low. Their 10-year survival is zero. We will treat
00:10:17.380 | them with a very aggressive regimen of multiple drugs. And again, you'll get a five-year survival
00:10:23.920 | of maybe 10% to 20%. And by 10 years, nobody's alive.
00:10:30.020 | If you take a person with stage three colon cancer, so the colon cancer is big and it's
00:10:37.140 | even in the lymph nodes around the colon. But at least grossly, you can't see those
00:10:45.140 | cells in the liver. Microscopically, of course, we know they're there. Because if you don't
00:10:49.680 | treat those patients, they still die of colon cancer. But you whack them with the same chemo
00:10:54.520 | regimen that you were going to give the metastatic patients, 80% of those people are alive in
00:10:59.180 | five years.
00:11:00.820 | So night and day difference in survival. What's the difference? In the person with metastatic
00:11:06.060 | cancer, you're treating a person with hundreds of billions of cells. In the adjuvant setting,
00:11:12.660 | which is what we call it adjuvant when you treat people who have only microscopic disease,
00:11:18.360 | you're treating billions of cells. The same is true with breast cancer. So we have the
00:11:22.660 | clinical trial data to put them side by side. So rule number one is don't get cancer. Rule
00:11:29.100 | number two is catch cancer as early as possible if you're going to get it. Which brings us
00:11:33.460 | to your question of how do you screen for it? We basically screen, the first line of
00:11:39.660 | screening is imaging, is a sort of visualization. So you have cancers that occur outside the
00:11:45.680 | body that you can look at directly. So skin cancer, you can look directly at the skin.
00:11:51.180 | Esophageal, gastric, colon cancer, those are outside the body, right? Mouth to anus embryologically
00:11:56.540 | is outside the body. So you can put a scope in and you can look directly at the cancer.
00:12:03.100 | But for all other cancers that are inside the body, yeah, you have to rely on some sort
00:12:06.040 | of imaging modality. Although now we're starting to look at things called liquid biopsies.
00:12:10.800 | So blood tests that are looking for cell-free DNA. And the cell-free DNA gives us a sense
00:12:16.460 | of based on the epigenetic signature of what you're looking at, hey, is there a cancer
00:12:22.140 | in the body? And if so, what tissue is it potentially coming from based on these epigenetic
00:12:26.080 | signatures? So the problem with relying on any one modality is a problem of sensitivity
00:12:34.520 | and specificity optimization. Now with MRI scanners, which are in some ways the best
00:12:40.580 | way to do this because they don't have radiation. So you don't want to be incurring damage as
00:12:44.640 | you do this. The irony of doing a whole body CT scan to screen for cancer is your whole
00:12:50.620 | body CT scan would be close to 30 to 50 millisieverts of radiation. It's a staggering sum of radiation.
00:12:57.760 | So does that mean that people should, sorry to pull you off this, but I was going to ask
00:13:04.440 | about this anyway, avoiding going through the whole body scanner at the airport?
00:13:09.400 | Noise. So low. So low. Yeah. Going through a whole body scanner at the airport or even
00:13:14.920 | getting a DEXA scan. I mean, these are trivial amounts of radiation.
00:13:18.440 | What about flying? You hear that pilots get more cancer.
00:13:23.880 | If you're a pilot who's flying over the North Pole back and forth and back and forth, you're
00:13:28.640 | probably getting, you know, five to 10 millisieverts a year. The NRC suggests that nobody should
00:13:34.840 | get more than 50 millisieverts a year. So you and I both travel a fair amount, but
00:13:40.640 | typical travel for the busy person, let's say two round trip flights of more than two
00:13:48.080 | hours per month and an international trip every three months.
00:13:52.400 | Probably still less than a millisievert a year. Yeah. Living at sea level, one millisievert
00:13:57.320 | a year, living at a mile elevation. If you lived in Denver, you're at two millisieverts
00:14:01.240 | a year. I have to ask standing in front of the microwave.
00:14:05.040 | I'm just, we've got friends. They ask. With or without testes on the counter.
00:14:12.380 | That's an inside joke that unfortunately and fortunately deserves no description. And Peter's
00:14:18.280 | not referring to me. But people worry about other sources of radiation. So it doesn't
00:14:24.000 | sound like the microwave is a concern. What are the other major sources of radiation?
00:14:29.600 | I mean, outside of sort of nuclear stuff where things go sadly wrong.
00:14:32.160 | You live near a plant or there's been a... Yeah, there's been a... It's mostly at the
00:14:36.440 | hands of medical professionals, right? It's the CT scanner and the PET scanner are hands
00:14:40.180 | down the biggest source of radiation. What about the x-rays at the dentist when
00:14:43.280 | they go... They're very low.
00:14:44.280 | When they scurry behind the wall, put me under the blanket.
00:14:47.040 | They're very low, relatively speaking. Fluoroscopy is very high. They tend to try to cover up
00:14:54.720 | all of you that... So for example, if they were doing a fluoroscopic study of your kidney
00:14:59.760 | because you had a stone or if you were getting an injection into, you know, if they were
00:15:04.200 | doing a fluoroscopic guided injection of one of your discs in your neck, that would be
00:15:09.280 | a locally pretty high dose. But they're going to cover the hell out of you elsewhere. And
00:15:13.760 | again, if you get one of these things, it's not the end of the world. But boy, I wouldn't
00:15:17.440 | want to be getting one a month. And back to the point about screening, you know, a chest
00:15:22.280 | abdomen pelvis CT scan is probably... I mean, look, there's probably a scanner out there
00:15:28.440 | now that's moving fast enough that it's much lower. But I'll give you an example. Okay.
00:15:31.800 | Remember how I talked about we do CT angiograms on all of our patients for coronary artery
00:15:36.480 | disease? An off-the-shelf scanner for this is 20 millisieverts of radiation.
00:15:44.120 | Okay. So calibrate, calibrate me because...
00:15:46.520 | That's 40% of your annual allotment.
00:15:48.920 | Oh, wow. So the medical practitioners really are the major culprits here.
00:15:55.240 | That's right. So what we say is, and I think most doctors are now realizing this is, no,
00:16:02.160 | no, it behooves you to pay a little bit more to go to a really good place that can do that
00:16:08.040 | scan for two millisieverts. Meaning they have a much faster CT scanner, much better software,
00:16:15.280 | and they're better engineers. So they have better engineering that they can do on the
00:16:18.800 | scanner to get that done. So if someone listening to this, here's my take. Do not get a CT scan
00:16:25.680 | or any imaging study without asking, how much radiation am I seeing? And if a person can't
00:16:30.600 | tell you how many millisieverts of radiation you're being exposed to, then just say, I'm
00:16:34.320 | going to wait a minute until somebody can tell me that.
00:16:36.840 | I realize...
00:16:38.400 | And keep in mind, if 50 is the most you should ever be exposed to in a year, there better
00:16:44.680 | be a damn good reason why I'm going to get 25 in a day. Now, there are some people who
00:16:48.200 | have to do this. If you're a cancer patient and they're scanning you as a part of your
00:16:53.680 | treatment, you have to pick and choose between those two opportunities. So I also don't want
00:17:00.120 | to create some fear mongering where, oh my God, if you hit 50 in a year, you're hosed.
00:17:03.880 | No, it's just I wouldn't want to hit 50 a year every year for my whole life. And I certainly
00:17:07.840 | wouldn't want to be hitting hundreds a year for any period of time.
00:17:11.920 | I think we're just trying to raise awareness and also calibrate people to what the sources
00:17:16.840 | are and so they can make good choices, not to place them into a chronic state of fear.